Method of insolubilizing the surface of carbohydrate derivative bodies



Patented June 29, 1954 METHODOF INSOLUBILIZIN G THE SURFACE OFCARBOHYDRATE DERIVATIVE BODIES William B. Hewson, Wilmington, Del.,assignor t Hercules Powder Company, Wilmington, Del., a corporation ofDelaware No Drawing. Application June 30, 1951, Serial No. 234,679

Claims.

This invention relates to organic solventsoluble carbohydratederivatives having substituted anhydroglucose repeating units in whichsubstituents having unsaturated groups dimerizable by peroxide catalystsare present and more particularly to the insolubilization of saidcarbohydrate derivatives by catalytic dimerization of the functionalgroups.

Numerous organic solvent-soluble carbohydrate derivatives havingsubstituents which are unsaturated and capable of interaction of thepolymerization type by being subjected to polymerization conditions areknown. Cellulose acetate methacrylate and allyl cellulose are typicalexamples. The interest in these derivatives lies in their capability ofbeing insolubilized by a polymerization or cross-linking reactionbetween unsaturated groups of adjacent molecules. The insolubilizationhas heretofore been effected by mixing a polymerization catalyst such asan organic peroxide with the carbohydrate derivative and subsequentlyheating at a temperature adequate for efiecting cross-linking, or byexposing the surface of a shaped article of such material to ultravioletlight so as to insolubilize the surface by a cross-linking reaction. Ineither case the insolubilizing treatment requires uneconomically longperiods of time. I

Now in accordance with the present invention, it has been found thatorganic solventsoluble carbohydrate derivatives of this type which areamenable to cross-linking reactions are rendered insoluble in organicsolvents with substantial improvement in time and temperaturerequirements by heating the carbohydrate derivative in contact with anaqueous liquid swelling medium containing dissolved therein about 0.005to about 5% of a peroxygen compound capable of catalyzing polymerizationreactions at a temperature within the range of about 40 C. to about 150C. The insolubilization is carried out on the carbohydrate deriva tivein the form of a shaped body and the insolubilization may vary in degreeinwardly from the surfaces and will be greatest at the surfaces whereactivation due to contact with the swelling agent and catalyst hasaccelerated the crosslinking reaction to the greatest degree.

The insolubilization process is carried out by compounding an organicsolvent-soluble carbohydrate derivative having substitutedanhydrogluoose repeating units, in which the substituents includeunsaturated functional groups .dimerizable by peroxide catalysts and thedegree of.

substitution of said substituents is suflicient to functional effectinsolubilization by dimerization or crosslinking thereof, and forming ashaped body whose surfaces are to be insolubilized, and heating thesurface of the shaped body at a temperature within the range of about 40C. to 150 C. in contact with an aqueous swelling medium containing about0.005 to about 5% of a peroxygen compound capable of catalyzingpolymerization'reactions in this temperature range dissolved therein.The heating is continued until any desired degree of insolubilizationof' the surface is achieved.

The following examples illustrate the method of insolubilization asapplied to certain organic solvent-soluble carbohydrate derivativeshaving substituted anhydroglucose repeating units in which there aresubstituents having unsaturated functional groups dimerizable byperoxide catalysts. All parts and percentages unless otherwisedesignated are by weight.

Example I Cellulose acetate sorbate having a sorboyl D. S. (degree ofsubstitution) of 0.09 and a total degree of substitution (acetyl andsorboyl) of about 3 was prepared by moistening 100 parts cellulose with52.5 parts glacial acetic acid and mixing with 1875 parts methylenechloride, 972 parts acetic anhydride and 322 parts of a mixture preparedby heating together equal parts of sorbic acid and acetic anhydride andas a catalyst 2.7 parts 72% perchloric acid admixed with 4.9 parts zincchloride solution. This mixture, after kneading in an acetylator at22-25 C. for 16 hours, was then worked up by adding 5.8 parts 32%kneading and subsequently diluting the reaction dope with acetone andpouring the resulting solution into anhydrous methanol. The cellu-, loseacetate sorbate was obtained as a precipitate which was purified bywashing with methanol and then with water and finally was dried in airat 30 C. This triester showed, by bromine titration for unsaturation,the presence of sorboyl groups in an amount corresponding to ness ofabout 3 mils was cast from this solution A and dried in air at 30 C. Onesample of this film was rendered insoluble in methylene chloride-ethanol(9:1) by heating at C. in boiling aqueous 20% ethanol containing 0.1%benzoyl peroxide for about 10 minutes.

aqueous sodium acetate with continued Example II Samples of celluloseacetate sorbate films (0.05 sorboyl D. S., 2.2 acetyl D. S.) were heatedat 80 C. in a 20% solution of ethanol in water con taining dissolvedtherein 0.067% benzoyl peroxide based on the weight of the solution.Samples were withdrawn at intervals to determine the time required forsurface insolubilization of the film in methylene chloride-ethanol(9:1). The minimum time required was 0.5 minute. The melting point (ParrBar) of a film treated in this manner was increased from 211 C. for anuntreated film to 226 C. for a film treated 10 minutes and to 230 C. fora film treated for 20 minutes.

Example III Cellulose acetate propionate sorbate was prepared by mixing20 parts cellulose which had been pretreated with 10 parts of aceticacid with 3.62 parts sorbic acid and a mixture of 101 parts propionicanhydride, 166 parts methylene chloride, 0.16'part 72% perchloric acid,and 0.43 part 70% zinc chloride solution. After 72 hours mixing at roomtemperature, parts 32% sodium acetate solution was added and mixing wascontinued for minutes. The resulting dope was diluted with acetone andprecipitated by pouring into anhydrous methanol. The precipitate waswashed alternately with methanol and water and then dried for 3 hours invacuo at 65 C. The resulting triester had an acetyl D. S. of about 0.2,propionyl D. S. of about 2.72, and sorboyl D. S. of 0.08. The resultingtriester was soluble in methylene chloride-ethanol (9:1) and was madeinto a 5% solution in that solvent. A film having a thickness of 3 milswas cast from this solution. A sample of the film was insolubilized byminutes heating at 80 C. in ethanol containing 0.1% benzoyl peroxide forcomplete insolubilization.

Example IV Cellulose acetate sorbate having a total acyl D. S. of about2.6 was prepared in the following manner: 100 parts cellulose moistenedwith parts glacial acetic acid was mixed with 13.6 parts sorbic acid andwas then kneaded with a mixture of 417 parts methylene chloride, 180

parts acetic anhydride, and 1.25 parts 95.5% suliuric acid dissolved in66.7 parts acetic anhydride for 1.2 hours while the temperature wasallowed to rise gradually to about -52 C. After 7.5 hours kneading theacylation reaction was stopped by the addition of 67 parts waterfollowed by continued kneading for 15 hours. The acetylated mixture wasthen hydrolyzed by kneading with 7.66 parts 95.5% sulfuric aciddissolved in 8.75 parts acetic acid for 6 hours at ail-52 C. and bycontinued kneading for 2 hours after the addition of 87 parts 32% sodiumacetate. The partially hydrolyzed ester was isolated by removing themethylene chloride under reduced pressure and then kneading the productwith fresh water. The resulting product was ground while wet and washedthoroughly with water and finally dried at -90 C. This product had asorboyl D- S. 0.06 and an acetyl D. S. of 2.49. It was readily solublein an acetone-ethanol solution (9:1). A 25% solution of this ester in96% acetone (4% water) was made up and, after filtration and deaeration,was spun into a yarn of 92 denier, 28 filament with a one-half twist perinch. This yarn was spun under tension and was dried by hot air GOO-120C.) Samples of the yarn were heated at 85 C. in a 20% solution ofethanol in water containing dissolved therein 0.1% benzoyl peroxide.Complete insolubilization of the yarn in methylene chlorideethanol (9:1)was achieved by 20 minutes of such treatment. The insolubilized yarn wasinsoluble in chlorinated dry cleaning solvents.

Example V A film of cellulose acetate crotonate was cast from a solutionof cellulose acetate crotonate (crotonyl D. S. 0.4, acetyl D. S. 2.2).The film after drying at 30 C. was soluble in methylene chloride-ethanol(9:1) and was rendered com pletely insoluble in that solvent mixture byheating at about C. for 20 minutes in a 20% solution of ethanol in watercontaining 0.1% benzoyl peroxide.

Example VI A film of allyl starch (allyl D. S. about 2) was cast from anacetone solution of allyl starch. The resulting film was soluble inbutyl acetate. A sample of the film after heating for about 20 minutesin boiling 20% aqueous ethanol containing 0.07% benzoyl peroxidedissolved therein was completely insoluble in butyl acetate.

Example VII A film of ethyl cellulose acrylate (acrylate D. S. about0.2, ethyl D. S. 2.4) was soluble in a 4:1 toluenezethanol mixture. Asample of the film after heating for 20 minutes in a 5% aqueous ethanolsolution containing 0.1% benzoyl peroxide was almost completelyinsoluble in 1:1 toluenetethanol mixture.

The insolubilization process of this invention has been found to beapplicable to all organic solvent-soluble carbohydrate derivativeshaving substituents which are unsaturated and capable of interaction ofthe polymerization type when subjected to polymerization conditions. Asfurther examples of such carbohydrate derivatives, the following aretypical: cellulose acetate methacrylate, cellulose propionatemethacrylate, cellulose acetate acrylate, cellulose propionate acrylate,cellulose crotonate, cellulose acetate crotonate, cellulose stearatecrotonate, cellulose acetate tiglate, cellulose acetate cinnamate, andthe corresponding starch esters and, in general. esters of polymerizableunsaturated acids and cellulose or starch, esters of polymcrizableunsaturated acids and partially substituted cellulose and starch esters,or esters of polymerizable unsaturated acids and partially substitutedstarch or cellulose ethers or hydroxy alkyl ethers of cellulose orstarch. Similarly the process is applicable to the ethers of theaboveclesignated partially substituted cellulose derivatives wherein theunsaturated eher group is a polymerizable ether group. The unsaturatedpolymerizable acid groups with which cellulose and starch derivativesmay be substituted for the production of carbohydrate derivativesoperable in the process of this invention include acrylic acid, methacrylic acid, crotonic acid, tiglic acid, sorbic acid, undecylenic acid,cinnamic acid, monoethyl maleate, monomethyl maleate, and similarunsaturated acids. Where the substituent of the organic solvent-solublecarbohydrate derivative is an unsaturated ether group, the unsaturatedether groups which may be present in such carbohydrate derivativesinclude the following: vinyl, allyl, methallyl, crotyl, and the like.The unsaturated substituents may be all identical or they may be mixedand there may be present both unsaturated ester groups and unsaturatedether groups.

The amount of unsaturated substituents, i. e., their degree ofsubstitution, in the carbohydrate derivative will vary with thecharacter of the un- Y saturated substituent as is well known in theart.

Many of these carbohydrate derivatives having polymerizable unsaturatedgroups are well known in the art and have heretofore been insolubilizedby heating in the dry state or by exposing to ultraviolet light in thedry state and the D. S. of the unsaturated substituents required forinsolubilization is substantially the same in the present process as inthe prior art processes. The cellulose derivatives may be completely orpartially substituted.

The insolubilization process of the present invention depends upon thepresence of a catalyst in the aqueous swelling medium with which theinsolubilizable carbohydrate derivative is treated, said polymerizationcatalyst being capable of efiecting a cross-linking or polymerizationwithin the temperature of the treatment. Peroxygen compounds are themost desirable catalysts. The polymerization catalyst is preferably anorganic peroxide such as benzoyl peroxide, perbenzoic acid, acetylperoxide, peracetic acid, cumene hydroperoxide, and t-butylhydroperoxide. Inorganic peroxygen compounds such as potassiumpersulfate, sodium persulfate, hydrogen peroxide, sodium perborate, andthe like may also be used. The amount of catalyst in the swelling mediumwill be a small effective amount usually within the range of about 0.005to about 5.0%.

The present process is utilized for insolubilizing formed articles orshaped bodies of the insolubilizable carbohydrate derivative. Theseformed articles or shaped bodies may be in various forms such as films,filaments, fibers, hollow bodies, coatings on formed articles or shapedbodies, solid shaped bodies, and the like, the surfaces of which areexposed and amenable to swelling by contacting with a swelling agent.

The insolubilization process appears to be dependent upon provision of ameans for penetration of the catalyst or of the free radicals producedby the catalyst into the solid shaped body. It is believed that underthe conditions of swelling provided by the swelling medium, catalyticactivity is improved by the swelling action of the swelling agent on thesurface of the shaped body, because of the greater mobility of thecross-linkiIlggroups and of the catalyst in the swollen plastic. Forsurface insolubilization the depth of penetration of the swelling agentneed not be great and in any process in which surface insolubilizationtakes place, partial insolubilization to varying depths within theshaped body will also be effected to varying degrees depending upon thetemperature ofinsolubilization, the nature of the swellin agent, thenature of the carbohydrate derivative, and the activity of the catalyst.In the case of thin films, filaments of small diameter, and the like,particularly where the swelling agent can reach all surfaces, theinsolubilization is generally readily effected throughout the shapedbody.

The swelling agents which are effective in the process of this inventionare aqueous solutions of organic solvents, whichsolvents in the purestate alone or in combination would swell or dissolve the cellulosederivative. The organic solvent or swelling agent is preferably onewhich is volatile at 100 C. so that it is readily evaporated from thesurface of the formed body. The presence of water is important, and inany swelling composition which the organic solvent is a good solvent forthe cellulose derivative, it is im-. portant that water be present insufficient amount to inhibit solubilization completely. In any suitablecomposition there appears to be a minimum useful amount of water whichis within the range of about 30 to about 40% of the swelling medium,and'the amount must be sufficient to prevent permanent distortion of theshaped form by the organic solvent. The swelling medium may containsubstantial amounts of water and it may be an aqueous solution of anorganic solvent containing from as low as about 5% of the organicsolvent but preferably about 10 to about 30% organic solvent. Theorganic solvents which may be used in the swelling medium includesubstantially all of the lower molecular weight volatile water-miscibleorganic solvents. Examples of such solvents are methanol, ethanol,propanol, isopropyl alcohol, acetone, dioxane, glycol, tbutyl alcohol,acetic acid, and monomethyl and monoethyl ethers of glycol and glycerol.Suitable aqueous swelling media will vary in composition with thecarbohydrate composition involved but will be readily selected by oneskilled in the art.

The temperature which is used in the insolubilization process is anytemperature within the range from that required to activate thepolymerization catalyst up to about 150 C. The lower temperature rangevaries somewhat with the catalyst and appears to be dependent upon thetemperature required for breakdown of the catalyst into free radicals.This minimum temperature will generally be within the range of about 40to C; A convenient temperature range for the insolubilization process isthe refluxing temperature of the particular swelling medium used whenoperating under atmospheric pressure. This temperature will generally bewithin the range of about 50 C. to about C. Temperatures above 100 C.may be used'in a closed system under pressure.

The process of insolubilization of the surface of the shaped bodiescomprising the insolubilizable carbohydrate derivatives in accordancewith this invention generally involves submerging the shaped body intothe aqueous swelling medium at the selected temperature for a sufficientlength of time to effect insolubilization of at least the surface of theshaped body. In such a process the swelling medium contacts the surfacesof the shaped body and it is those surfaces which are contacted whichare insolubilized first. If desired, the insolubilization process may becontinued to efiect insolubilization to varying depths from the surface.In the case of continuous films or filaments, the insolubilizationprocess may be carried out by continuously passing the film or filamentthrough a bath of the aqueous swelling medium, or a loosely coiledbundle and skein of the film or filament may be treated batchwisesubmerged in the aqueous swelling medium. The greatest advantages of thepresent process are attained when the surfaces of the shaped body arecontacted with the aqueous swelling medium in the liquid state.

Among the many advantages of the present process is the outstandingincrease in speed of the insolubilization which makes mulch lowertemperatures practical for the first time. This is a distinctimprovement over the prior art dry heating processes of insolubilizationor crosslinking of unsaturated carbohydrate derivatives containing'dissolved catalyst 1 because'xof the ireducedtendency toward degradationofthe prod-- not in prolongedheating. The'present process isparticularly advantageous where incorporation of the catalyst intheunsaturated cellulose'derivative inaccordance with the prior' art wouldinvolve treatment at sufficiently high temperature, as in milling orkneading operations, to cause premature cross-linking before-the-finalshaped body is produced whose surfaces are to be insolubilized.'A'further advantage is that scrap material which has not beeninsolubilized is re-usable without the danger of polymerization duringreworking such as would obtain ii a catalyst were present in the scrapmaterial.

This application is a continuation-in-part of my copending application,Serial No. 203,797, filed December 30,1950.

What I claim and desiretoprotect by Letters Patent is:

l. The method of rendering insoluble in organic solvents the surface-ofa shaped body wherein said surfacecomprises-essentially a catalyst-freeorganic solvent-soluble carbohydrate derivative of a carbohydrate ofthe, group consisting of celluloseand starch having substitutedanhydroglucose repeating units in which substituents selected from the'groupzconsisting of ethersand esters and having ethylenic typeunsaturated functional groups dirnerizable by peroxygen compounds arepresent and the degree of substitution'of said substituents is in therange of about 0.06 to about .2 and is-sufficient to effectinsolubilization bydirnerization thereof, which comprises heatingsaidsurface at a temperature within the range of about 40 C. to about150 C. in contact with an aqueous swelling "medium capable of swellingbut not dissolving said derivative selected from the group consisting ofwater and water containingup toabout 70%of a water-m scible volatileorganic'solvent, containingdissolved therein'in small amount within therange of about 0.005% to about 5% based on the weight of theswelling-medium of .a'peroxygen compound capable of catalyzingpolymerization reactions in said temperature range, until said surfaceis rendered insoluble in-said organic solvents.

zcThemethodof rendering insoluble in' organic solvents the surface-ofashaped body wherein said surface comprises'essentially a catalyst-freeorganic solvent-soluble carbohydrate derivative of a carbohydrate of thegroup consisting of 'cellulose and starch having substitutedanhydroglucose repeating units inwhichsubstituents selected from thegroup consisting of ethers and esters and having ethylenic typeunsaturated functional groups dimerizable by peroxygen compounds arepresent and the degree of substitution of said substituents is in therange of about 0.06 to about 2 and is sufficient to effectinsolubilization by dimerization thereof, which comprises heating .saidsurface at a temperature within the range of about 40 C. to about-150 C.in contact with an aqueous swelling medium capable of swelling but notdissolving vsaid derivative, selected from the group consisting of waterand water containing up toabout'70% ota watermiscible volatile organicsolvent, containing dissolved therein insmall amount within the range ofabout 0.005% to about'5% based on the weight of the swelling medium ofan-organic peroxide capable of catalyzing polymerization reactions insaid-ternperature range, until said surface is rendered insolublein saidorganic solvents.

=3. Theimethodnofrendering insoluble" organic solvents the surface of ashaped body wherein said surface comprises essentially a catalyst-freeorganic solvent-soluble Y carbohydrate derivative of-arcarbohydrate ofthe group consisting of'cellulose' and starch having substitutedanhydroglucose repeating units in which substituents selected fromthegroup consistingof' ethers and esters having ethylenic type unsaturatedfunctional groups 'dimerizable by peroxygen compounds are present 'andthe degree of substitution of said substituents 'is in'the range ofabout 0.06 to about'2 and is suflicient to effect-insolubilizationbydimerization thereof, which comprises heating said surface at atemperature within the range of about 40 C. to about C. in contactwithan aqueous swelling medium, selected from the group consisting of waterand water containing up to about 70% of a watermiscible volatile organicsolvent, containing'dissolved" therein in smallamount within theirangeof about 0.005% to about 5%based on the weight of the swelling medium ofbenzoyl peroxide capable of catalyzing polymerization reactions in-saidtemperature range, until said-surface is rendered insoluble in saidorganic solvents.

"4. Themethod of rendering insoluble in organic solvents the surface ofa shaped -'body wherein said surface comprises essentially acatalyst-free organic solvent-soluble "carbohydratederivativeera-carbohydrate of the group consisting of cellulose andstarch having'substituted anhydroglucose repeating units in whichsubstituents selected from the group consisting of ethers and esters andhaving ethylenictype unsaturated functional groups dimerizable byperosygen compoundsfare present and the'degree of substitution of saidsubstituents is in the range of about 0.06 to about '2 and is sufiicientto eifect insolubilization by dimerization thereof, whichcomprisesheating said surface at a'temperature within the range of'about40 C. to about 150 C. in contact with a dilute aqueous organicsolvent containing dissolved therein inan'amount within the range ofabout 0.005% to about5% based on the weight ofthe" swelling medium of aperoxygen compound capable of catalyzing polymerization-reactions insaid temperature range, said-aqueous organic solventbeing capable ofswelling but not dissolving said carbohydrate derivative and comprisinga water-miscible volatile organic solvent and 15-80% water in an amountsufficient to allow the aqueous organic solvent to swell but notdissolve' the carbohydrate derivative, untilsaid surface is renderedinsoluble in said organic solvents.

5. The-method of rendering insoluble-in organic solvents the surface ofa shaped body wherein said surface comprises essentially a catalyst-freeorganic solvent-soluble cellulose derivative having substitutedanhydroglucose'repeating units in which substituents-selected from thegroup consisting'of ethers and esters and having ethylenic typeunsaturated functional groups dimerizable .by-peroxygen compounds arepresentand the degree of substitution of said substituents is in therange ofabout 0.06 to about 2 and is sufiicient to effectinsolubilization by dimerization thereof, which comprises heating saidsurfaceat -a temperature within the range of about-40 C. to'about 150C.in contact with an aqueous swelling medium capable of "swelling but notdissolving said derivative, selected fromthe group consisting of waterand water containing up toabout 7 0% of :a water-miscible volatileorganic solvent, containing dissolved therein a small amount within therange of about 0.005% to about 5% based on the weight of the swellingmedium of a peroxygen compound capable of catalyzing polymerizationreactions in said temperature range, until said surface is renderedinsoluble in said organic solvents.

6. The method of rendering insoluble in organic solvents the surface ofa shaped body wherein said surface comprises essentially a catalyst-freeorganic solvent-soluble starch derivative having substitutedanhydroglucose repeating units in which substituents selected from thegroup consisting of ethers and esters and having ethylenic typeunsaturated functional groups dimerizable by peroxygen compounds arepresent and the degree of substitution of said substituents is in therange of about 0.06 to about 2 and is sufficient to effectinsolubilization by dimerization thereof, which comprises heating saidsurface at a temperature within the range of about 40 C. to about 150 C.in contact with an aqueous swelling medium capable of swelling but notdissolving said derivative, selected from the group consisting of waterand water containing up to about 70% of a water-miscible volatileorganic solvent, containing dissolved therein a small amount within therange of about 0.005% to about 5% based on the weight of the swellingmedium of a peroxygen compound capable of catalyzing polymerizationreactions in said temperature range, until said surface is renderedinsoluble in said organic solvents.

7. The method of rendering insoluble in organic solvents the surface ofa shaped body wherein said surface comprises essentially a catalyst-freeorganic solvent-soluble cellulose acetate sorbate having a sorboyl D. S.in the range of about 0.06 to about 2 which comprises heating saidsurface at a temperature within the range of about 40 C. to about 150 C.in contact with an aqueous swelling medium capable of swelling but notdissolving said derivative, selected from the group consisting of waterand water containing up to about 70% of a watermiscible volatile organicsolvent, containing dissolved therein a small amount within the range ofabout 0.005% to about 5% based on the Weight of the swelling medium anorganic peroxide capable of catalyzing polymerization reactions in saidtemperature range, until said surface is rendered insoluble in saidorganic solvents.

8. The process of claim 4 in which the watermiscible organic solvent isethanol.

9. The process of claim 4 in which the watermiscible organic solvent isacetic acid.

10. The process of claim 4 in which the watermiscible organic solvent isacetone.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,322,575 Hill June 22, 1943 2,336,985 Freund Dec. 14, 19432,396,165 Ernsberger Mar. 5, 1946 2,406,369 Hamilton et a1 Aug. 27, 19462,539,920 Morgan Jan. 30, 1951 2,558,047 Gloor June 26, 1951

1. THE METHOD OF RENDERING ISOLUBLE IN ORGANIC SOLVENTS THE SURFACE OF ASHAPED BODY WHEREIN SAID SURFACE COMPRISES ESSENTIALLY A CATALYST-FREEORGANIC SOLVENT-SOLUBLE CARBOHYDRATE DERIVATIVE OF A CARBOHYDRATE OF THEGROUP CONSISTING OF CELCULOSE AND STARCH HAVING SUBSTITUTEDANHYDROGLUCOSE REPEATING UNITS IN WHICH SUBSTITUENTS SELECTED FROM THEGROUP CONSISTING OF ETHERS AND ESTERS AND HAVING ETHYLENIC TYPEUNSATURATED FUNCTIONAL GROUPS DIMERIZABLE BY PEROXYGEN COMPOUNDS AREPRESENT AND THE DEGREE OF SUBSTITUTION OF SAID SUBSTITUENTS IS IN THERANGE OF ABOUT 0.06 TO ABOUT 2 AND IS SUFFICIENT TO EFFECTINSOLUBILIZATION BY DIMERIZATION THEREOF, WHICH COMPRISES HEATING SAIDSURFACE AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 40* C. TO ABOUT 150*C. IN CONTACT WITH AN AQUEOUS SWELLING MEDIUM CAPABLE OF SWELLING BUTNOT DISSOLVING SAID DERIVATIVE SELECTED FROM THE GROUP CONSISTING OFWATER AND WATER CONTAINING UP TO ABOUT 70% OF A WATER-MISCIBLE VOLATILEORGANIC SOLVENT, CONTAINING DISSOLVED THEREIN IN SMALL AMOUNT WITHIN THERANGE OF ABOUT 0.005% TO ABOUT 5% BASED ON THE WEIGHT OF THE SWELLINGMEDIUM OF A PEROXYGEN COMPOUND CAPABLE OF CATALYZING POLYMERIZATIONREACTIONS IN SAID TEMPERATURE RANGE, UNTIL SAID SURFACE IS RENDEREDINSOLUBLE IN SAID ORGANIC SOLVENTS.